How do I stop getting jealous of other girls talking to my brother?

He's not my biological brother;although, he's my brother in the spirit. I love him, he's my closest family, he's my homey and I just like him as a whole.Sometimes girls talk to my brother and it makes me a bit jealous. Being jealous is not a cute look... at all. However, I get scared they'll take my brother from me. Although he gives me all his time, tells me how much he likes being around me, tells me he loves me and will unfriend a girl in a heart beat for me.I kind of got jealous because a girl added him on Facebook, I told him I felt jealous because she had curly hair like me and he added her. He reassured me everything was fine. I started thinking of a time some girl was tyring to brush up on my brother.After I calmed down I realized how desperate and crazy I sounded. I am ashamed of my actions. I just don't want to lose my friend, even though deep down in my heart he's my brother and he won't ever leave me.I am so glad God brought him into my life, it's bringing me to tears. I don't want to be jealous of him adding other girls on social media. I usually block them or avoid visiting his pages to keep the jealoust down.

If that is some religious thing then I am sorry for offending you. If not, just because you are close doesn't mean you are spiritually family. That ruins the definition of a "brother" and breaks it's purpose.